The mother of Achilles was Thetis, a sea-nymph of the Nereid class, daughter of the old man of the sea, Nereus. Thetis was one of the fifty Nereids, the beautiful sea-maidens who were the daughters of Nereus and Doris, and she was famous for her wisdom, her kindness, and her power over the waters. According to prophecy, Thetis was destined to bear a son greater than his father, and this prophecy caused both Zeus and Poseidon to abandon their pursuit of her, lest they be overthrown by their own son. Thetis was then married to the mortal king Peleus, and she became the mother of the greatest of Greek heroes, Achilles.
The Prophecy of Thetis
The prophecy concerning Thetis was the central fact of her life. According to the prophecy, Thetis was destined to bear a son who would be greater than his father. This prophecy alarmed both Zeus and Poseidon, both of whom had courted Thetis. To prevent the prophecy, Thetis was married to the mortal Peleus, and she resisted her divine suitors.
The myth is told in several ancient sources, including the Iliad and the Bibliotheca of Apollodorus. In the Iliad, Thetis herself tells Achilles of the prophecy: “I bore you under an evil fate, you who were short-lived beyond all others, doomed to die young.”
The Marriage of Thetis and Peleus
The marriage of Thetis and Peleus was a major event in Greek myth. According to the most familiar version, all the gods were invited to the wedding except Eris, the goddess of strife. Eris, in her anger, threw a golden apple inscribed “to the fairest” into the midst of the guests, leading to the Judgment of Paris and, eventually, the Trojan War.
Peleus, with the help of Chiron the centaur, captured Thetis by holding onto her while she tried to escape. Thetis, who was shape-shifting, turned into various forms, including a lion, a serpent, and a cuttlefish, but Peleus held on until she finally submitted. The marriage of Thetis and Peleus was a stormy one, and Thetis eventually left Peleus to return to the sea.
The Children of Thetis
Thetis had several children by Peleus, but most of them died in infancy. According to the myth, Thetis tried to make her children immortal by anointing them with ambrosia and holding them in the fire to burn away their mortality, but Peleus, horrified, stopped her. The only child who survived was Achilles, whom Thetis tried to make immortal by dipping him in the river Styx, the river that separated the world of the living from the world of the dead. The waters made him invulnerable except at the heel where she held him.
According to one version of the myth, Thetis had seven sons by Peleus, and six of them died in infancy, leaving only Achilles. The other children were burned by the fire in which Thetis tried to make them immortal, or were otherwise lost. The story has been used by some scholars to explain the Greek concept of hero cults, in which the dead were believed to have divine power.
Thetis and Achilles in the Iliad
In the Iliad, Thetis plays a major role. She is a frequent visitor to her son’s side, and she is the one who pleads with Zeus on his behalf, asking the king of the gods to favor the Trojans until the Greeks learn to honor Achilles. She is also the one who fetches the new armor for Achilles, forged by Hephaestus after the death of Patroclus.
Thetis is one of the most sympathetic figures in the Iliad, a mother who is helpless to prevent her son’s death, but who does everything she can to make his short life as glorious as possible. The scene in which she mourns the death of Patroclus, or the death of Achilles himself in later sources, is among the most poignant in Western literature.
The Cult of Thetis
Thetis was worshipped as a goddess in several places, particularly in Thessaly, where she was associated with the cult of Apollo. The temple of Thetis at Spercheios, in Thessaly, was centers of her cult. She was also worshipped in other parts of the Greek world, particularly in coastal cities and in regions where the sea was important to the local economy.
The Romans identified Thetis with their own goddess Thetis, who was the consort of the sea-god Oceanus. The cult of Thetis in Rome was particularly associated with the family of the emperor, who claimed descent from the goddess through Aeneas and the line of the Trojan kings.
The Legacy of Thetis
The figure of Thetis has had a powerful influence on Western culture. The image of the mother who tries to make her child immortal, and who is helpless to prevent his death, has been used by countless writers, artists, and philosophers. The phrase “Achilles’ heel,” derived from the myth of Thetis dipping her son in the river Styx, has become a standard metaphor for any critical weakness.
In modern fiction, Thetis appears in countless novels, films, and video games, including the Percy Jackson series, the God of War video game franchise, and many other modern retellings. She is also a major figure in Mary Zimmerman’s play Metamorphoses (2002), which is a modern adaptation of the myths of Ovid.
For more on the mythological context, see our profile of Achilles, our guide to the Greek heroes, and our profile of Patroclus. For more on the cultural legacy, see our guide to Greek mythology in modern culture.